How much fuel?

[peabody]

Hi
I have completed assembly of a Brodak Ringmaster ARF.
29 ounces. 3 ounce uniflow tank. 58' (eye to eye) .015 lines
OS .20 per Brett Buck

It seems to fly pretty well...maybe I'll move the leadouts forward to improve overhead line tension.

The main issue is that the thing runs closer to 15 minutes than 5. Is this normal, or have I screwed something up?

Thanks

[Dane Martin]

My S1 is 24 oz with an os25 la.
I usually only run 2 - 2.5 oz if I'm practicing the pattern. Otherwise it runs forever. The os20 is an awesome engine for that! 3 oz might just be a little much.

[Tim Wescott]

On an APC 9-4 prop I get about the same fuel consumption that Dane reports.

I fly on 60 foot lines, because I feel that a fast plane on long lines flies better than the same plane at the same lap time on shorter lines.  But then, I build heavy.  Your mileage may vary.

[Brett Buck]

Hi
I have completed assembly of a Brodak Ringmaster ARF.
29 ounces. 3 ounce uniflow tank. 58' (eye to eye) .015 lines
OS .20 per Brett Buck

It seems to fly pretty well...maybe I'll move the leadouts forward to improve overhead line tension.

The main issue is that the thing runs closer to 15 minutes than 5. Is this normal, or have I screwed something up?

   Depending on the fuel, but say 10% nitro and 18% oil (like SIG)  it's around 1.75-2 ounces for a comfortable full pattern.

   Brett

[FLOYD CARTER]

Also, if you set the engine for a screaming run, it will probably be too lean.  This will make it run forever!  Set it just so it barely breaks from a 4 cycle into a 2 cycle. 

[peabody]

Thanks...I'll play with it this weekend...
I have never had much luck "short tanking" a plane.

Thanks again!

[Brett Buck]

Also, if you set the engine for a screaming run, it will probably be too lean.  This will make it run forever!  Set it just so it barely breaks from a 4 cycle into a 2 cycle. 

  This engine is set to a medium to nearly-peaked 2-stroke and runs that way through the flight. It is peaked, and then backed off 5-6 clicks until it just shows a distinct speed drop. It will not work very well if you run it close to a 4-stroke.

    Brett

[Pat Chewning]

It seems to fly pretty well...maybe I'll move the leadouts forward to improve overhead line tension.

I'm just a beginner, but don't you move the lead-out lines back to improve overhead line tension?

[Bill Johnson]

I'm just a beginner, but don't you move the lead-out lines back to improve overhead line tension?

Yes.

[peabody]

Moving them forward reduces yaw.

[Curt D Contrata]

   Depending on the fuel, but say 10% nitro and 18% oil (like SIG)  it's around 1.75-2 ounces for a comfortable full pattern.

   Brett

Brett,
Just on the sidelines listening in but... Didn't you previously suggest a clunk tank? Are you short filling or is there a clunk tank that small?
Also and another curiosity, is all of this the same for both the ABC and the iron piston versions of the .20FP?

Curt

[Steve Helmick]

I'm just a beginner, but don't you move the lead-out lines back to improve overhead line tension?

No, not normally. Typically, most of us start with the LO's too far aft, the model yaws and slows down. Keeping the speed up also keeps the line tension up. So, getting yaw to minimum works best, whether that means moving the LO's forward or aft. From the pilot's position, you can sight down the LE, flap hingeline, etc. to get an idea if the yaw is minimal. Hang the model from a rafter by the leadouts...it should hang nose down a wee bit.

You might also notice your engine taking multiple laps to quit, while burping. Plane is yawed out, thus tank is yawed out. As the engine quits, the nose comes in, the tank again feeds fuel to the engine, it takes off again, etc., etc., until it finally, really, and for the last time, runs dry. Sucks! Many guys build their tanks with taper (bigger in the back), or install the tank with the aft end skewed outward. And of course, make sure your engine is running rich enough in level flight that it will not be sagging lean when overhead. The prop makes a huge difference.    Steve

[Brett Buck]

I'm just a beginner, but don't you move the lead-out lines back to improve overhead line tension?

  No, or at least usually not. That will usually crab the airplane sideways and reduce the line tension overhead.

     Brett

[Brett Buck]

Brett,
Just on the sidelines listening in but... Didn't you previously suggest a clunk tank? Are you short filling or is there a clunk tank that small?
Also and another curiosity, is all of this the same for both the ABC and the iron piston versions of the .20FP?

     A clunk tank works fine, and that is what I have been using of late. . I partially fill it, usually by eye, since you can see the fuel inside. I have a Sullivan SS-4 right now. The other advantage is that you can put 1/2 ounce of fuel in it for very short training flights. The cut-off is typically irritating, of course.

     I don't know about the iron-liner fuel consumption, I have only run the ABC versions long enough to figure out how much fuel to use. The iron-liner runs OK when you get it working, but it seems to be much fussier about fuel, as you might expect.

      Brett

     

[Dennis Moritz]

You have to hit the leadout position right. If leadouts are two far forward airplane can fly yawed nose in when high on the hemisphere. Weight of lines pulling nose towards the pilot. A point made to me at the NATs by Tom Dixon. In this case I had leadouts set too far forward on my Oriental. Creeping them back improved overhead tension. Very noticeable.

[Steve Fitton]

Rich, is this the same engine that you set the Philly Contest duration record with on that green Clown ARF?

If it is it might have some issues, because that means its been running 15-20 minutes routinely.

Anyone who has an iron piston FP 20 or 25 should at least try it.  I put an iron piston FP-25 in a Brodak Tomahawk and it ran pretty much *exactly* as Brett's setup said it should run.  Got a pile of trophies with that plane and motor, probably the best spent 20 bucks for a powertrain in my career.

[peabody]

Hi Steve...
Fooling with it today in a gale, I put two ounces of fuel in it.
One tank of purple 10/22 Powermaster yielded 5 minutes of run
Another tank (again 2 ounces) of fuel that I got when Bill Rich retired got me 4 minutes....
Both flights were with the needle backed out a bit but still in a 2 stroke more.
It was a red stupid clown....
Have fun!

[Bill Little]

Hi Brett, Rich, and everyone else! hahaha  The first OS .20FP-BBTU I had was an iron piston version.  I did not notice a huge difference in fuel consumption between it and the later ABN versions I have run, including a Dirty Dan Special.  I pull out about 1/2oz. when practicing and closer to 3/4 oz. at Huntersville when contest flying.  Oh yes, it is a 3 oz. tank and 5% nitro Sig 1/2 and 1/2 oil.

BIG Bear
RNMM/AMM

[Dennis Moritz]

Rich, are you getting a black exhaust residue? Engine may be breaking in. Depending upon clearances, crank as well as p/l might be running in and running hot. This is happening to me with a recent Tower 40. Much to my surprise. Since I always thought ABN and ABC engines were pretty much plug and play. Half a tank run and you are good to go. This Tower has been breaking in for 20 flights plus. As it breaks in it used more fuel, has more power, and a more controllable break.